JP2007333981A - Alignment layer, alignment layer sheet, polarized light separating sheet and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: an alignment layer which hardly blocks at a back surface of a base material film even when the layer is stored after it is rolled; an alignment layer sheet in which the alignment layer is supported by the base material film; a polarized light separating sheet which is constituted by layering a resin layer with cholesteric regularity on the alignment layer of the alignment layer sheet; and a liquid crystal display device having the polarized light separating sheet. <P>SOLUTION: The alignment layer constitutes: the polarized light separating sheet which includes the alignment layer sheet which is constituted by layering the alignment layer on the base material film; and the resin layer which is layered on the alignment layer of the alignment layer sheet and which has cholesteric regularity. The alignment layer has a surface of arithmetic mean roughness of 0.001 μm to 1.0 μm, and is formed of a mixture containing a polymer and particulates. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides an alignment film on which a resin layer having cholesteric regularity can be formed, an alignment film sheet in which the alignment film is supported by a base film, and a cholesteric material on the alignment film of the alignment film sheet The present invention relates to a polarization separation sheet formed by laminating regular resin layers and a liquid crystal display device having the polarization separation sheet.

In a liquid crystal display device, a polarizing element is used as an optical member that polarizes light from a light source to improve light use efficiency in the liquid crystal display device. This polarizing element is comprised from a multilayer film, and the polarization separation sheet is used as the main component.
The polarized light separating sheet has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropy. (Linearly polarized light separation type), such as an orientation film of cholesteric liquid crystal polymer or an orientation liquid crystal layer supported on a film substrate, reflects either the left-handed or right-handed circularly polarized light and transmits the other light Have been proposed (circularly polarized light separation type) (see, for example, Patent Documents 1 and 2).

  The circularly polarized light separation type polarization separation sheet has a configuration in which an alignment film is laminated on a base film, and a resin layer having cholesteric regularity is laminated on the alignment film. This polarized light separating sheet is obtained by laminating an alignment film such as a polyvinyl alcohol film on a base film, rubbing the surface of the alignment film, and applying and drying a resin composition that exhibits cholesteric regularity. ,It is formed.

  The alignment film sheet in which the alignment film is formed on the base film is usually fed out from the base material roll 2 in which the long base film 1 is rolled as shown in FIG. It is obtained by forming the alignment film 3 on the base film 1 in a continuous process. This long alignment film sheet 4 is rolled and stored as an alignment film sheet original roll 5.

  As shown in FIG. 5, the rolled alignment film sheet 4 is fed from the alignment film sheet raw roll 5 in the polarization separation sheet production line when the polarization separation sheet is manufactured. The surface is rubbed. Subsequently, the resin layer 6 having cholesteric regularity is formed on the alignment film 3 by applying and curing a resin composition exhibiting cholesteric regularity such as a cholesteric liquid crystal composition on the surface of the rubbed alignment film 3. Is formed, and the polarization separation sheet 7 is obtained.

Japanese Patent No. 3373374 JP-A-11-002722

  In response to the report that a product with variations in optical characteristics is obtained in the polarization separation sheet manufactured as described above, the present inventors have investigated the cause. As a result, while the alignment film sheet was stored as a raw fabric roll, the exposed surface of the alignment film laminated on the base film was locally blocked on the back of the base film. It turned out to be.

  As shown in FIG. 6, on the surface of the alignment film 3 on the alignment film sheet 4 fed out from the alignment film sheet raw roll, a portion 3a that was not blocked by the air entrained when the raw roll was formed, and air It was found that there were scattered portions 3b that were blocked on the back surface of the base film without any interposition.

  The surface of the alignment film 3 of the alignment film sheet 4 in such a surface state is rubbed to form a liquid crystal composition layer 6 containing a polymerizable liquid crystal compound as shown in FIG. When the orientation of the layer 6 is examined, the location 6a with good orientation and the location 6b with insufficient orientation are scattered, the location 3a where the blocking is not present, and the location 3b where the blocking is performed. It was confirmed that it corresponds exactly to. It has been found that since the portion 6b having insufficient orientation occurs, the optical characteristics of the produced polarization separation sheet vary.

  The present invention has been made in view of the above-described conventional problems, and the problem is that an alignment film that is difficult to block on the back surface of a base film, even when stored in rolls, is based on the alignment film. An alignment film sheet supported by a material film, a polarization separation sheet in which a resin layer having cholesteric regularity is laminated on the alignment film of the alignment film sheet, a method for producing the same, and the polarization separation sheet An object of the present invention is to provide a liquid crystal display device.

  In order to solve the above-described problems and achieve the object, an alignment film according to the present invention is formed by stacking an alignment film on an alignment film on a base film, and an alignment film on the alignment film sheet. An alignment film used for a polarized light separation sheet comprising a resin layer having cholesteric regularity, the arithmetic average roughness of the surface of which is 0.001 to 0.1 μm, and the mixture includes a polymer and fine particles It is formed.

  The alignment film sheet according to the present invention is an alignment film sheet in which an alignment film is laminated on a base film, and the alignment film is the alignment film of the present invention.

  In addition, the polarization separation sheet according to the present invention includes an alignment film sheet in which an alignment film is laminated on a base film, and a resin layer having cholesteric regularity that is laminated on the alignment film of the alignment film sheet. The alignment film according to the present invention is characterized in that the alignment film is the alignment film of the present invention.

  The liquid crystal display device according to the present invention includes the polarization separation sheet of the present invention.

  Since the surface of the alignment film according to the present invention is adjusted to a specific surface roughness, even if it is stored on a roll after being laminated on the base film, blocking to the back of the base film is possible. Hard to occur. Therefore, when a material for forming a resin layer having cholesteric regularity is applied to the surface after rubbing and polymerized, a resin layer with good orientation without variation in orientation can be obtained. Therefore, by using the alignment film of the present invention, the alignment film sheet on the surface of which the alignment film is difficult to block even when stored in a roll form, and a resin layer having cholesteric regularity having good alignment properties are included. And a liquid crystal display device with good display characteristics.

  As described above, the alignment film according to the present invention includes an alignment film sheet obtained by laminating an alignment film on a base film, and a resin having a cholesteric regularity laminated on the alignment film of the alignment film sheet. An alignment film comprising a polarizing separation sheet comprising a layer, the surface having an arithmetic average roughness of 0.001 to 0.1 μm, and formed of a mixture containing at least a polymer and fine particles To do.

  Below, the alignment film of this invention and the alignment film sheet | seat by which this alignment film is laminated | stacked on a base film are demonstrated in detail.

(Alignment film and alignment film sheet)
FIG. 1 shows an alignment film 10 of the present invention and an alignment film sheet 11 of the present invention in which the alignment film 10 is formed on a substrate film 1. In FIG. 1, the main part of the state in which the long alignment sheet 11 is wound and stored is shown. In the present invention, the long means that it is long enough to be wound in a roll shape, and preferably 1 m or more. As shown in FIG. 1, the alignment film 10 of the present invention is formed on the surface 1a of the base film 1, and the arithmetic average roughness of the surface 10a is 0.001 μm to 0.1 μm, and 0.005 μm. It is preferable to be in the range of ~ 0.05 μm. When the arithmetic average roughness of the surface 10 a of the alignment film 10 is less than 0.001 μm, when the alignment film sheet 11 composed of the base film 1 and the alignment film 10 is rolled, it is aligned on the back surface 1 b of the base film 1. Although the surface 10a of the film 10 may partially block, blocking can be prevented by adjusting the thickness to 0.001 μm or more. When the arithmetic average roughness exceeds 0.1 μm, good rubbing is not realized when the alignment film 10 is rubbed. That is, the alignment control force suitable for the alignment of the liquid crystal composition containing the polymerizable liquid crystal compound laminated thereon is given to the alignment film surface by rubbing, but the arithmetic average roughness of the alignment film is 0.1 μm. If it exceeds the range, application of the orientation regulating force may be hindered. The arithmetic roughness is an average value of values measured at three points along the width direction of the sheet in accordance with JIS B0601. The three points along the width direction are the three points of the intermediate point in the width direction of the sheet and two points located on the inner side by 10% of the total width from each end of both ends. The position along the longitudinal direction of the sheet to be measured in the width direction is an intermediate position of the length in the longitudinal direction of the sheet. That is, the arithmetic roughness of the alignment film was determined by measuring the surface roughness according to JIS B0601 at three points along the width direction of the sheet at the middle position of the total length in the longitudinal direction of the alignment film sheet. It is the value obtained by calculating the value.

  The average thickness of the alignment film 10 is preferably in the range of 0.05 μm to 2 μm, and more preferably in the range of 0.1 μm to 1 μm. The average thickness of the alignment film is obtained by measuring the thickness of the alignment film at three points along the width direction of the sheet at the middle position of the total length in the longitudinal direction of the alignment film sheet, and obtaining the average value. Value. The three points in the width direction are, as in the case of the arithmetic roughness described above, two points located on the inner side by 10% of the full width from each end of both ends of the sheet in the width direction of the sheet. Three points.

(Particle shape and dimensions)
It is important that the surface roughness that plays the role of preventing blocking in the alignment film 10 is uniform and uniform in the entire area of the surface 10a. This is because the fine particles 13 are uniformly dispersed in the polymer layer 12. It is realized by doing. The uniform dispersion of the fine particles 13 in the polymer improves as the shape of the fine particles 13 becomes closer to a true sphere. In the alignment film 10 of the present invention, in order to obtain suitable fine particle dispersibility, the ratio of the major axis to the minor axis of the microparticles 13 is preferably 1: 1 to 2.5: 1. It is more preferably ˜2: 1, and particularly preferably 1: 1 to 1.5: 1. The ratio of the major axis to the minor axis is determined by observing the particle shape with a transmission electron microscope, measuring the major axis and minor axis for 10 particles, and determining the average value of the major axis and minor axis. By bringing the ratio of the major axis to the minor axis closer to 1: 1, that is, closer to a true sphere, the contact area of the fine particles is reduced, aggregation is suppressed, and dispersion is facilitated.

  The particle diameter of the fine particles 13 is preferably a number average primary particle diameter in the range of 0.001 μm to 0.1 μm, and more preferably 0.005 μm to 0.05 μm in number average primary particle diameter. Further, the secondary particle diameter of the fine particles 13 is preferably 0.1 μm to 4.0 μm, and more preferably 0.2 μm to 1.0 μm. When the number average primary particle diameter is less than 0.001 μm, it becomes difficult to adjust the surface roughness of the alignment film 10 to 0.001 μm or more, and uniform dispersion is difficult to perform easily. Further, when the number average primary particle diameter exceeds 0.1 μm, the secondary particles of the fine particles become large in size, and it becomes difficult to adjust the surface roughness of the alignment film 10 to 0.1 μm or less.

(Fine particle material)
Examples of the material of the fine particles 13 include inorganic oxides such as silicon dioxide, zinc oxide, aluminum oxide, bismuth oxide, cerium oxide, cobalt oxide, tin oxide, yttrium oxide, barium oxide, zirconium oxide, strontium oxide, and antimony oxide; acrylic Resins such as resin, polystyrene resin, and melanin resin can be used. Among these, inorganic oxides are preferable, and silicon dioxide, aluminum oxide, and zinc oxide having good dispersibility are more preferable.
The content of the fine particles is preferably 0.1 to 5 parts by weight, more preferably 0.25 to 2.5 parts by weight, with respect to 100 parts by weight of the polymer that is the alignment film base material, and 0.4 to 1. 5 parts by weight is particularly preferred.

(Polymer and other components forming the alignment film)
The polymer forming the polymer layer 12 that is the base material of the alignment film 10 is preferably a water-soluble polymer and an alcohol-soluble polymer. Further, the mixture having the polymer and the fine particles 13 preferably contains a low molecular compound having a primary amino group and / or a secondary amino group. The water-soluble polymer is a polymer that dissolves in an amount of 0.5 g or more in 100 g of water at 25 ° C. The alcohol-soluble polymer is a polymer that dissolves in an amount of 0.5 g or more in 100 g of ethanol at 25 ° C. Moreover, a low molecular compound is a compound with a molecular weight of 100-1500.

  By further containing the low molecular compound in the mixture, the adhesion between the alignment film obtained from the mixture and the resin layer having cholesteric regularity can be improved. In addition, by including this low molecular compound, the surface hardness of the alignment film surface to be obtained is lowered, and blocking during storage in a roll shape is likely to occur. However, in the alignment film of the present invention, since blocking is appropriately suppressed by mixing fine particles having a predetermined shape and a predetermined size, the adhesion between the alignment film 10 and the resin layer having cholesteric regularity, and the base of the alignment film 10 The normally contradictory characteristics of preventing blocking of the back surface of the material sheet 1 can be simultaneously obtained.

(Polymer material)
Examples of the water-soluble and alcohol-soluble polymers include polyvinyl alcohol, modified polyvinyl alcohols such as terminal thiol-modified polyvinyl alcohol and silane-modified polyvinyl alcohol, polysaccharides such as methylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose, and gelatin.
Of these exemplified polymers, polyvinyl alcohol is most suitable. The polyvinyl alcohol used in the present invention is not limited by its saponification degree, but preferably has a saponification degree of 85 to 95%.

  The degree of polymerization of these polymers is 50 to 3000, preferably 80 to 2000, and more preferably 100 to 1000. When the polymerization degree of the polymer is less than 50, the alignment regulating force of the liquid crystal molecules is weak, and the adhesion between the base sheet 1 and the alignment film 10 is deteriorated. On the other hand, if it exceeds 3000, the solubility in water or an alcohol solvent will be poor, and the coating properties will be insufficient.

(Low molecular compound)
Examples of the low molecular weight compound having a primary amino group and / or a secondary amino group include 1-aminopentane, 1-aminohexane, 1-aminooctane, 2-aminooctane, 1,5-dimethylhexylamine, 2, 2-dimethyl 1,3-propanediamine, 2-ethylhexylamine, n-heptylamine, n-hexylamine, 1,1,3,3-tetramethylbutylamine, bis (2-methoxyethylamine), 3-butoxypropylamine 3-ethoxypropylamine, 1-methoxy-sec-butylamine, 3-n-propoxypropylamine, tetrahydrofurfurylamine, 3-methylthiopropylamine, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylmethoxysilane Aminop Primary amines such as propylethyldiethoxysilane, glucosamine, oligoglucosamine; bis (2-ethylhexyl) amine, Nn-butylethylamine, di-n-amylamine, di-iso-amylamine, di-n-butylamine, Di-sec-butylamine, di (2-ethylhexyl) amine, di-n-hexylamine, diisobutylamine, diisopropylamine, di-n-propylamine, 3,3′-methyliminobispropylamine, Nn-butyl Ethanolamine, diethanolamine, diisopropanolamine, N- (2-hydroxyethyl) ethylenediamine, 2,2′-iminodiethanolamine, bis (2-ethoxyethyl) amine, N- (2-methoxyethyl) ethylamine, N- (2 -Methoxyethyl) isopropyl Secondary amines such as amine, N- (2-methoxyethyl) -n-propylamine; bis (6-aminohexyl) amine, N, N-bis (3-aminopropyl) methylamine, 3,3-diaminodi Propylamine, 3- (dibutylamino) propylamine, 2-diethylaminoethylamine, 3-diethylaminopropylamine, diethylenetriamine, N, N-dimethyl-1,3-propanediamine, dipropylenetriamine, hexamethylenediamine, tris (2- Aminoethyl) amine, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, n-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, Primary amino groups and secondary amines such as polyamines Compounds having an amino group; and the like.

  Among these, 3-ethoxypropylamine, 3-n-propoxypropylamine, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylmethoxysilane, aminopropylethyldiethoxysilane, glucosamine, oligoglucosamine, 3 -Aminopropylmethyldimethoxysilane, n-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane are preferred.

The molecular weight of the low molecular weight compound is 100-1500, preferably 200-1000. When the molecular weight of the low molecular weight compound is less than 100, the volatility becomes high, and the handleability in the coating process is deteriorated. On the other hand, when the molecular weight of the low molecular compound exceeds 1500, the compatibility with the polymer and the solubility in various solvents deteriorate, and the characteristics become insufficient.
The low molecular weight compound preferably has one or more hydrophilic substituents in the molecule so as to have solubility in water and / or a lower alcohol solvent.
Examples of the hydrophilic substituent include an alkoxyl group, a hydroxyl group, an ether group, a hydroxysilyl group, and an alkoxysilyl group.

  The mixing ratio of the polymer and the low molecular compound having an amino group is preferably in the range of 99: 1 to 75:25 in terms of molar ratio. When the mixing ratio of the low molecular weight compound having an amino group is less than 1 mol%, the adhesion to the liquid crystal polymerized layer (resin layer) having cholesteric regularity becomes insufficient. Moreover, when the mixing rate of the low molecular compound which has an amino group exceeds 25 mol%, when apply | coating the polymeric liquid crystal composition mentioned later, a coating stripe will generate | occur | produce and a surface state will deteriorate.

(Base film)
The base film 1 is preferably a transparent resin film made of a transparent resin material. The transparent resin film is preferably subjected to plasma discharge treatment and corona discharge treatment in order to improve wettability at the time of coating the alignment film and adhesion between the base film and the alignment film. It is also preferable to provide an adhesive layer (undercoat layer) on the base film in order to improve the adhesion between the base film and the alignment film.

The transparent resin is not particularly limited as long as it has a total light transmittance of 70% or more measured with a 2 mm-thick plate smooth on both sides based on JIS K7361-1. For example, polyethylene, propylene-ethylene copolymer, polypropylene, polystyrene, a copolymer of an aromatic vinyl monomer and an acrylic acid alkyl ester having a lower alkyl group, a methacryl having an aromatic vinyl monomer and a lower alkyl group. Examples thereof include a copolymer with an acid alkyl ester, polyethylene terephthalate, terephthalic acid-ethylene glycol-cyclohexanedimethanol copolymer, polycarbonate, an acrylic resin, and a resin having an alicyclic structure. In addition, (meth) acrylic acid is acrylic acid and methacrylic acid.
The average thickness of a base film is 1-1000 micrometers normally, 5-300 micrometers is preferable and 30-100 micrometers is more preferable.

(Polarized light separation sheet)
In the polarization separation sheet of the present invention, after the surface of the alignment film 10 of the alignment film sheet 11 is rubbed, a liquid crystal composition that forms a resin layer having cholesteric regularity is applied on the rubbed surface, and the coating film is applied. By forming the alignment resin layer by polymerization and curing, the basic structure can be obtained. The rubbing method is not particularly limited, and examples thereof include a method of rubbing the alignment film in a certain direction with a roll made of a synthetic fiber such as nylon or a natural fiber such as cotton or a felt. In order to remove the fine powder (foreign matter) generated when rubbing and clean the alignment film surface, it is preferable to clean the formed alignment film with isopropyl alcohol or the like.

(Liquid crystal composition forming a resin layer having cholesteric regularity)
The resin layer having cholesteric regularity is preferably a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound.

(Polymerizable liquid crystal compound)
Examples of the polymerizable liquid crystal compound constituting the liquid crystal composition (resin composition) forming the resin layer having cholesteric regularity include compounds represented by the following formula (1).
^{R 3 -C 3 -D 3 -C 5} -M-C 6 -D 4 -C 4 -R 4 (1)
In the formula (1), R ³ and R ⁴ are reactive groups, and each independently represents an acryl group, a methacryl group, an epoxy group, a thioepoxy group, an oxetane group, a thietanyl group, an aziridinyl group, a pyrrole group, a vinyl group, It represents a group selected from the group consisting of allyl group, fumarate group, cinnamoyl group, oxazoline group, mercapto group, isocyanate group, isothiocyanate group, amino group, hydroxyl group, carboxyl group, and alkoxysilyl group. D ³ and D ⁴ are composed of a single bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkylene oxide group having 1 to 20 carbon atoms. Represents a group selected from the group; C ^{3 to} C ⁶ are a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C═N—. N = C -, - NHCO - , - OCOO -, - CH 2 COO-, and represents a group selected from the group consisting of -CH ₂ OCO-. M represents a mesogenic group, specifically, unsubstituted or halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, linear or branched alkyl group having 1 to 10 carbon atoms, halogenated One or more substituted alkyl groups, azomethines, azoxys, biphenyls, terphenyls, naphthalenes, anthracene, cyanobiphenyls, cyanophenyl esters, benzoates, phenyl cyclohexanecarboxylate 2-4 skeletons selected from the group of esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles -O-, -S-, -S-S-, -CO-, -CS- _{-OCO-, -CH 2 -, - OCH} 2 -, - C = N-N = C -, - NHCO -, - OCOO -, - CH 2 COO-, and coupled by a linking group of -CH ₂ OCO-, etc. To be formed.

  The liquid crystal compound has a Δn value of 0.18 or more, preferably 0.22 or more. When a compound having an Δn value of 0.30 or more is used, the absorption edge on the long wavelength side of the ultraviolet absorption spectrum may extend to the visible range, but desired optical performance even when the absorption edge of the spectrum extends to the visible range. It can be used as long as it does not adversely affect By having such a high Δn value, a polarization separation sheet having high optical performance can be provided.

  The liquid crystalline compound preferably has at least two or more reactive groups in one molecule. Specific examples of the reactive group include an epoxy group, a thioepoxy group, an oxetane group, a thietanyl group, an aziridinyl group, a pyrrole group, a fumarate group, a cinnamoyl group, an isocyanate group, an isothiocyanate group, an amino group, a hydroxyl group, and a carboxyl group. , Alkoxysilyl group, mercapto group, vinyl group, allyl group, methacryl group, acrylic group and the like. By having these reactive groups, a stable cured product can be obtained when the cholesteric resin composition used in the present invention is cured. When a compound having one or less reactive group in one molecule is used, when the cholesteric resin composition is cured, a crosslinked cured product cannot be obtained, so that a film strength that can withstand practical use cannot be obtained. Even when a cross-linking agent described later is used, the film strength is insufficient and practical use is difficult. The film strength that can be practically used is HB or more, preferably H or more, in pencil hardness (JIS K5400). If it is lower than HB, it is easy to be scratched and lacks handling properties. The upper limit of preferable pencil hardness is not particularly limited as long as it does not adversely affect the optical performance and durability test.

  The method of polymerizing the polymerizable liquid crystal compound to form a resin layer having cholesteric regularity is not particularly limited, but for example, on the support substrate subjected to alignment film formation and rubbing treatment as necessary, A method of applying and polymerizing a composition containing a polymerizable liquid crystal compound can be employed. Also, if necessary, a plurality of resin layers may be provided by repeating the coating-polymerization process a plurality of times to form a plurality of resin layers, or by laminating a plurality of laminates having a resin layer and a supporting substrate. Good. By providing a plurality of resin layers having different reflection bands, a polarization separation sheet having a wider reflection band can be obtained.

  In addition to the polymerizable liquid crystal compound, the liquid crystal composition containing the polymerizable liquid crystal compound includes a crosslinking agent, a photoinitiator, a surfactant, a chiral agent, a solvent, a polymerization inhibitor for improving pot life, and improved durability. Antioxidants, UV absorbers, light stabilizers and the like can be contained. The composition can be applied by a known method such as reverse gravure coating, direct gravure coating, die coating, or bar coating.

Moreover, the polymerization of the polymerizable liquid crystal compound in the composition can be performed by one or more heating and / or light irradiation. Specifically, for example, the heating condition may be a temperature of 40 to 140 ° C. and a time of 1 second to 3 minutes. The light used for light irradiation in the present invention includes not only visible light but also ultraviolet rays and other electromagnetic waves. Specifically, the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 second to 3 minutes. Moreover, it can also be set as a polarized light separation sheet | seat with a wide reflection zone by performing multiple times of ultraviolet irradiation-heating including the weak ultraviolet irradiation and heating of 0.01-50 mJ / cm < ² >, for example. For example, after performing the weak UV irradiation-heating process once or more, heating and / or light irradiation for finally curing the polymerizable liquid crystal compound is performed to form a resin layer having a wide reflection band. it can. Further, when the polarization separation sheet includes a plurality of resin layers, it is preferable to perform ultraviolet irradiation and heating a plurality of times for all the layers to widen the reflection band of each layer.

  Next, the polarization separation sheet of the present invention obtained using the alignment film sheet of the present invention will be described.

  FIG. 2 schematically shows the polarization separation sheet 20 of the present invention. In FIG. 2, a cholesteric resin layer 21 is laminated on the alignment film 10 laminated on the base material 1 of the alignment film sheet 11. The cholesteric resin layer 21 includes four layers having different pitches (each of the pitches P0, P1, P2, and P3). In FIG. 2, the pitch p is increased in the order of P0, P1, P2, and P3. In FIG. 2, only the chiral structure for one cycle of each cholesteric resin layer P0, P1, P2, and P3 is shown, but the chiral structure may be two cycles or more.

  When light is incident on the cholesteric resin layer 21 of the polarization separation sheet 20, only the left-handed or right-handed circularly polarized light in the specific wavelength region is reflected. Light other than the reflected circularly polarized light is transmitted. White light incident on the cholesteric resin layer 21 of the polarization separation sheet at an incident angle θ1 is refracted at the surface of the cholesteric resin layer 21 and is incident on the cholesteric resin layer 21 at a refraction angle θ2, and has a pitch P corresponding to the wavelength λ. One circularly polarized light in the cholesteric resin layer 21 is reflected at the reflection angle θ2, refracted on the surface of the cholesteric resin layer 21, and emitted at the emission angle θ1. Refraction is performed according to Snell's law.

As shown in FIG. 2, when the helical axis 22 representing the rotation axis when the molecular axis is twisted in the chiral structure and the normal line of the cholesteric resin layer 21 are parallel, the pitch (length) p of the chiral structure is The wavelength λ of the circularly polarized light to be reflected has the relationship of the following formula (2).
λ = n × p × cos θ2 (2)
Here, n = (ne + no) / 2 (wherein, no represents the refractive index in the minor axis direction of the polymerizable liquid crystal compound, and ne represents the refractive index in the major axis direction of the polymerizable liquid crystal compound).
Therefore, the reflection band of circularly polarized light reflected by the cholesteric resin layer 21 having the pitch p is expressed by the following formula (3).
no × p × cos θ2 ≦ λ ≦ ne × p × cos θ2 (3)

(Liquid crystal display device)
In the present invention, the polarization separation sheet 20 and the quarter wavelength plate are attached to a liquid crystal display device having at least a polarizer X, a liquid crystal cell, and a polarizer Y, and the polarizer X, the liquid crystal cell, the polarizer Y, By arranging the quarter-wave plate and the polarization separation sheet 20 in this order, a liquid crystal display device with improved luminance can be obtained.

  FIG. 3 is a diagram showing an example of the liquid crystal display device of the present invention. As shown in FIG. 3, the reflector 30, the cold cathode tube 31, the diffusion plate 32, the prism sheet (not shown), the polarization separation sheet 20, and the quarter wavelength plate 33 having a phase compensation function are the adhesive layer 34. The brightness enhancement film 35, the polarizer Y36, the liquid crystal cell 37, and the polarizer X38 are stacked in this order. The light from the light source includes right polarized light and left polarized light. When the light is incident on the polarization separation sheet 20, the circularly polarized light in one rotation direction (circularly polarized light in the right direction toward the traveling direction of light in the figure) is transmitted through the polarization separation sheet 20 while maintaining the rotation direction. . The other circularly polarized light in the rotation direction (in the figure, the circularly polarized light rotated counterclockwise toward the light traveling direction) is reflected by the polarization separation sheet 20 (the reflected circularly polarized light is rotated counterclockwise toward the light traveling direction). Remain). The transmitted circularly polarized light is converted into linearly polarized light parallel to the transmission axis of the polarizer Y 36 by the quarter wavelength plate 33 having a phase compensation function fixed to the polarization separation sheet 20. On the other hand, the reflected circularly polarized light is reflected by the reflection plate 30 disposed behind the light source 31 and is incident on the polarization separation sheet 20 again. In this way, the light emitted from the light source 31 is effectively used, and the display brightness of the screen can be improved.

  Polarizers X and Y used in the present invention are known polarizers used in liquid crystal display devices and the like. The polarizer used in the present invention transmits one of two linearly polarized lights intersecting at right angles. For example, a hydrophilic polymer film such as a polyvinyl alcohol film or an ethylene vinyl acetate partially saponified film adsorbed a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, the hydrophilic polymer film Examples include uniaxially stretched and dichroic substances adsorbed, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Other examples include a polarizer having a function of separating polarized light such as grid polarizer and multilayer polarizer into reflected light and transmitted light. Of these, a polarizer containing polyvinyl alcohol is preferred.

Although the polarization degree of the polarizer used for this invention is not specifically limited, Preferably it is 98% or more, More preferably, it is 99% or more. The average thickness of the polarizer is preferably 5 to 80 μm.
The polarization transmission axis of the polarizer X and the polarization transmission axis of the polarizer Y are arranged so as to sandwich the liquid crystal cell so as to be at right angles. Polarizer performance may change due to moisture absorption. In order to prevent this, a protective film is usually bonded to both sides of the polarizer X or Y.

  In a liquid crystal cell, a liquid crystal material is filled between two glass substrates provided with transparent electrodes facing each other with a gap of several μm, and a voltage is applied to this electrode to change the alignment state of the liquid crystal. It controls the amount of light passing through.

  The liquid crystal cell is classified according to a method (operation mode) for changing the alignment state of the liquid crystal substance. For example, a TN (Twisted Nematic) type liquid crystal cell, a STN (Super Twisted Nematic) type liquid crystal cell, or a HAN (Hybrid Alignment Nematic) type. Examples include a liquid crystal cell, an IPS (In Plane Switching) type liquid crystal cell, a VA (Vertical Alignment) type liquid crystal cell, an MVA (Multiple Vertical alignment type liquid crystal cell), and an OCB (Optical Compensated Bend) type liquid crystal cell.

  The quarter-wave plate used in the present invention gives a quarter-wave phase difference to incident light. The phase difference differs depending on the wavelength of incident light. In general, a quarter wave plate that gives a phase difference of a quarter wavelength near the center wavelength of visible light, for example, around 550 nm, is called a quarter wavelength plate. On the other hand, in the present invention, a broadband quarter-wave plate can be used. The broadband ¼ wavelength plate gives a phase difference of almost ¼ wavelength at any wavelength in the visible light region including wavelengths of 410 to 660 nm. Almost 1/4 means 0.15 to 0.40, preferably 0.18 to 0.36, and more preferably 0.20 to 0.30.

  Further, it is preferable to use a quarter wave plate having a phase compensation function. A quarter wavelength plate having a phase compensation function gives a phase difference of a quarter wavelength near 550 nm, and has a retardation Rth in the thickness direction of less than 0 nm, preferably −20 to −1000 nm (( = ((Nx + ny) / 2-nz) × d); nx, ny are in-plane main refractive indexes, nz is a main refractive index in the normal direction, and d is a thickness).

  As a broadband quarter-wave plate, for example, a half-wave plate that gives a half-wave phase difference near a wavelength of 550 nm and a quarter-wave plate that gives a quarter-wave phase difference near 550 nm are stacked. One having a D layer made of a material having a positive intrinsic birefringence value and an E layer made of a material having a negative intrinsic birefringence value, wherein the D layer and the E layer are molecularly oriented in the same direction. Can be mentioned. Further, a commercially available broadband retardation film WRF (manufactured by Teijin Ltd.) or the like can be used.

In the liquid crystal display device of the present invention, when the quarter wavelength plate is not provided with the phase compensation function as described above, it further has substantially no in-plane retardation Re and has a thickness direction letter. It is preferable that a phase compensation element having a retardation Rth in the range of −20 nm to −1000 nm, preferably −50 nm to −500 nm is provided between the polarization separation sheet of the present invention and the quarter wavelength plate. At this time, it is preferable that the phase compensation element and the quarter-wave plate are fixed.
The phase compensation element having Rth in such a range has a function of compensating for the phase difference of light incident obliquely on the quarter wavelength plate.

  In this phase compensation element, the main refractive indexes nx, ny, and nz are required to satisfy the relationships of nz> nx, nz> ny, and nx≈ny. The main refractive index can be measured by an automatic birefringence meter [for example, “KOBRA series” manufactured by Oji Scientific Instruments Co., Ltd.]. Note that nx≈ny means that the refractive index difference is usually within 0.0002, preferably within 0.0001, and more preferably within 0.00005.

In addition, the in-plane retardation Re (Re = (nx−ny) × d: nx, ny and d are as defined above) of this phase compensation element is usually 20 nm or less, preferably 10 nm or less. More preferably, it is 5 nm or less.
A phase compensation element having such optical characteristics can be obtained by stretching and orientation of a film comprising a layer of a material having a negative intrinsic birefringence value.

  The diffusion plate 32 is generally known as a plate having a function in which a particulate diffusion material is uniformly dispersed in a matrix such as a resin, thereby scattering and diffusing light. The prism sheet is generally known as a sheet having a function of narrowing light having a wide traveling direction due to scattering or the like in the normal direction of the sheet surface.

  In FIG. 3, a diffusion sheet may be interposed and fixed between the polarization separation sheet 20 and the adhesive layer 34, or between the adhesive layer 34 and the quarter wavelength plate 33 having a phase compensation function. The diffusion sheet is generally laminated on a transparent film so that the particulate diffusion material is uniformly dispersed, and is known as a sheet having a function of scattering and diffusing light.

  In the present invention, it is preferable that the polarization separating sheet 20 has light diffusibility on the surface of the quarter-wave plate 34 having a phase difference compensation function. The light diffusibility is a property of scattering and diffusing light. In order to provide light diffusibility, for example, a method of laminating a particulate diffusing material on the surface of the polarization separation sheet 20 so as to uniformly disperse, a method of uniformly dispersing a particulate diffusing material on a substrate, Or the method of bonding the said diffusion sheet 32 to the polarization separation sheet 20 etc. are mentioned.

  Examples of the present invention will be described below. In addition, this invention is not limited by the following examples.

(Examples 1-3 and Comparative Examples 1-5)
Corona discharge on one side of an alicyclic olefin polymer film (trade name “ZEONOR FILM”, manufactured by Optes Co., Ltd.) having a thickness of 100 μm, a width of 660 mm, and a length of 500 m so that the surface wetting index is 56 dynes / cm. Treated. This was used as a substrate film.

  Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval PVA226), fine particles, and low molecular weight compound having an amino group are mixed in a water / ethanol mixed solvent (mixing ratio (weight ratio) 70 / 30) was dissolved and prepared so that the solid content was 1% by weight. The prepared solution was applied to the surface of the base film subjected to the corona discharge treatment using a wire bar # 4, and heated and dried at 100 ° C. for 2 minutes. The coating film obtained by heating and drying is subjected to rubbing treatment in parallel with the longitudinal direction of the film to form an alignment film having an average thickness of 0.2 μm to obtain a long alignment film sheet, which is wound into a roll. I took it.

  Next, the sheet is fed out 1000 mm from the long alignment film sheet, and in the middle part (longitudinal direction 500 mm) in the longitudinal direction of 1000 mm, the central part (one place) in the width direction and 10% of the total width from each edge in the width direction Three measured values obtained by measuring with a surface shape measuring instrument (made by ULVAC, using a stylus type surface shape measuring device Dektak 6M) in accordance with JIS B0601, at a total of three places, two inside the length. The average value was obtained, and the average value was defined as the arithmetic average roughness of the alignment film surface.

The alignment film sheet wound up in a roll shape is fed out, and an application liquid (resin composition) for forming an optically anisotropic layer having the composition shown in Table 2 below is applied onto the alignment film using a wire bar # 6. Drying and orientation aging were carried out at 0 ° C. The dried and orientation-aged coating film was irradiated with ultraviolet rays at 70 mJ / cm ² (UV-A), held at 100 ° C. for 5 minutes, and then irradiated with ultraviolet rays at 150 mW / cm ² for 5 seconds to cure the coating film. Then, a resin layer having an average thickness of 3 μm and having cholesteric regularity was formed, and a polarization separation sheet A was obtained. The resin layer having the cholesteric regularity of the obtained polarized light separating sheet A had a light transmittance of 55% at 400 nm to 750 nm and a reflectance of 35%.

(Evaluation)
The following three items were evaluated for the polarized light separation sheets obtained in the respective examples and comparative examples.
(1) Blocking of base film and alignment film:
In a roll wound with a long film (alignment film sheet) coated with an alignment film, a position where the alignment film application surface and the non-application surface (rear surface) of the base film are stuck and a place where the film is not attached (air) It was visually observed whether or not there was a place including the. Further, the alignment film is rubbed, the coating liquid shown in Table 2 is applied, and the adhered (blocking) portion is not sufficiently aligned or does not exhibit a liquid crystal state, and the portion that has not adhered is oriented. Was visually observed, and it was confirmed that the sticking marks were caused by uneven alignment of the liquid crystal composition layer. The results are shown in Table 3 below. In the table, no sticking marks are indicated by ○, and sticking marks are indicated by ×.

(2) Appearance of resin layer having cholesteric regularity:
The evaluation results are shown in Table 3 below. In the table, a resin layer having cholesteric regularity with no cloudiness is indicated by ◯. Moreover, the thing which the cloudiness generate | occur | produced, the rubbing trace, and the application | coating stripe | line | column can be confirmed visually is shown by x.

(3) Adhesion determination:
The adhesion between the alignment film and the resin layer having cholesteric regularity was evaluated according to JIS K5600. On the coated surface, 100 square cuts of 1 mm pitch grids were made, and cellophane tape (manufactured by Nichiban Co., Ltd., CT24) was brought into close contact with the film with the finger pad and then peeled off. Judgment was expressed by the number of squares in the 100 squares that were not peeled. In the table, 100/100 indicates that the non-peeled square in 100 squares is 100 squares.

Example 4
By coextrusion of the methacrylic acid ester polymer composition A (glass transition temperature 105 ° C.) (b layer) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C.) (a layer) at a temperature of 280 ° C. A multilayer film having a three-layer structure of b layer / a layer / b layer and each layer having a thickness of 45/70/45 (μm) was obtained. This multilayer film was tenter uniaxially stretched at a stretching temperature of 128 ° C., a stretching ratio of 1.4 times, and a stretching speed of 10 m / min to obtain a stretched multilayer film (retardation film).
The retardation film obtained had a retardation Rth of -118 nm in the thickness direction and a retardation Re of 140 nm in the in-plane direction at a wavelength of 550 nm.

  The cholesteric regular resin layer side of the polarization separation sheet produced in Example 1 and the retardation film were bonded and fixed to obtain a brightness enhancement film. On the backlight unit consisting of a reflector, cold cathode tube, diffuser plate and prism sheet, the brightness-enhancing film is arranged so that the polarization separation sheet (A) side faces the diffuser plate, and iodine is adsorbed to polyvinyl alcohol. The obtained polarizer Y, TN type liquid crystal cell, and polarizer X similar to the polarizer Y were arranged in this order to produce a liquid crystal display device as shown in FIG.

  The liquid crystal display device was caused to emit light in the white display mode and observed from the light exit surface side. The display surface of the liquid crystal display device incorporating the retardation compensation element obtained according to the present invention is bright and has a good white display, with no coloration over the entire surface, as compared with a comparative liquid crystal display device in which no brightness enhancement film is disposed. Met.

  As mentioned above, since the surface of the alignment film according to the present invention is adjusted to a specific surface roughness, even if it is stored on a roll after being laminated on the base film, the base film Less blocking to the back. Therefore, a liquid crystal composition containing a polymerizable liquid crystal compound can be applied to the surface after rubbing to obtain a liquid crystal composition layer having good alignment with no variation in alignment. A resin layer having no cholesteric regularity can be obtained.

  By using the alignment film of the present invention, an alignment film sheet on which the alignment film on the surface is hard to block and a polymerizable liquid crystal composition layer having good alignment properties are polymerized and cured even when stored in a roll shape. It is possible to provide a polarization separation sheet comprising a resin layer having cholesteric regularity and a liquid crystal display device having good display characteristics.

It is a section lineblock diagram of the orientation film sheet of the present invention formed by laminating the orientation film of the present invention on a substrate film, and is the figure showing the important section of the state laminated in the shape of a roll. It is explanatory drawing which shows the structure and function of the polarization separation film concerning this invention. It is a disassembled perspective view which shows the structure of the liquid crystal display device of this invention. It is explanatory drawing of the state by which the orientation film sheet obtained by forming an orientation film in a base film is wound up by the roll. It is explanatory drawing of the process by which the resin composition which forms the resin layer which has a cholesteric regularity is apply | coated and hardened after the alignment film of the alignment film sheet extended | stretched is rubbed, a resin layer is formed, and a polarization separation sheet is obtained. is there. It is a top view of the orientation film sheet which shows the surface state of the orientation film sheet after having been drawn | fed out from the roll of the orientation film sheet. It is explanatory drawing which shows the orientation state of the surface of the resin layer which has the cholesteric regularity formed on the alignment film shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film 1a Surface 1b Back surface 2 Base film original fabric roll 3 Alignment film 3a The location which was not blocked 3b The location which was blocked 4 Alignment film sheet 5 Alignment film sheet original fabric roll 6 Liquid crystal composition containing polymeric liquid crystal compound Physical layer 6a Location with good orientation 6b Location with poor orientation 7 Polarization separation sheet 10 Alignment film of the present invention 10a Surface of alignment film 11 Alignment film sheet of the present invention 12 Polymer layer 13 Fine particles 20 Polarization separation film 21 Cholesteric Resin layer having regularity 10 Light reflector 31 Cold cathode tube 32 Diffuser plate 33 1/4 wavelength plate having phase compensation function 34 Adhesive layer 35 Brightness enhancement film 36 Polarizer B
37 Liquid crystal cell 38 Polarizer A

Claims (10)

An alignment film used for a polarization separation sheet comprising an alignment film sheet in which an alignment film is laminated on a base film, and a resin layer having a cholesteric regularity laminated on the alignment film of the alignment film sheet There,
An alignment film having an arithmetic average roughness of a surface of 0.001 to 0.1 μm and formed of a mixture containing a polymer and fine particles.   2. The alignment film according to claim 1, wherein a ratio of a major axis to a minor axis of the fine particles is 1: 1 to 2.5: 1.   3. The alignment film according to claim 1, wherein the number average primary particle diameter of the fine particles is in a range of 0.001 μm to 0.1 μm.   The alignment film according to claim 1, wherein the polymer is a water-soluble polymer and an alcohol-soluble polymer.   The alignment film according to any one of claims 1 to 4, wherein the mixture further contains a low molecular compound having a primary amino group and / or a secondary amino group. An alignment film sheet in which an alignment film is laminated on a base film,
The alignment film according to claim 1, wherein the alignment film is the alignment film according to claim 1.   The alignment film sheet according to claim 6, wherein the alignment film sheet is long and is wound and stored. A polarization separation sheet comprising an alignment film sheet obtained by laminating an alignment film on a base film, and a resin layer having cholesteric regularity laminated on the alignment film of the alignment film sheet,
The polarizing film according to claim 1, wherein the alignment film is the alignment film according to claim 1.   The polarization separation sheet according to claim 8, wherein the resin layer having cholesteric regularity is a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound.   A liquid crystal display device comprising the polarization separation sheet according to claim 8.

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